[tools] Add a toolchain to cross compile for windows from mac and linux

[runtime] Add beginRenderVisuals and endRenderVisuals events (which allow to draw overlays before submitting the whole frame)

[unity] Fix shaders being transpiled over and over again even if they didn't change

[clay] Fix shaders being transpiled over and over again even if they didn't change

[tools] Allow deep array/object equality with Equal.equal() with an additional argument

[runtime] Allow deep array/object equality with Equal.equal() with an additional argument

Minor soloud custom backend change

[runtime] Improve clipper2-based implementation: use object pooling, use `Float` instead of `Int64` on js target

[runtime] Replace `Line` internals from `polyline` to `clipper` (more robust implementation, adds support of round caps and joins)

[runtime] Fix handling of closed paths in Graphics class

[runtime] Better handling of looping lines

[clay] Fix web path after change

[clay] Another attempt to handle RPI shader loading

[clay] Patch GLSL version from context version instead of hardcoded defines

Prepare 2.1.0 release